A bid is underway to reintroduce the platypus to Adelaide's River Torrens more than 40 years after the duck-billed monotreme's extinction on the South Australian mainland.
The project has been launched as part of a government push to establish the state capital as a National Park City.
Green Adelaide will lead the development of a scoping study to return the platypus to the river, which flows from the Adelaide Hills, by the city CBD and empties 85 kilometres on, into Gulf St Vincent.
SA Environment and Water Minister David Speirs says bringing the iconic mammal back has been dreamt of for at least two decades.
"The River Torrens has come a long way," he said.
"With today's improved native vegetation and water quality, it is the right time to progress this exciting project to hopefully make this dream a reality."
Mr Speirs said the platypus' reintroduction would not only support its survival but boost tourism and aid the long-term health of the river.
"Adelaide has just been ranked the most liveable city in Australia and third most liveable city in the world and projects like this will help further enhance this reputation," he said.
Now listed as a threatened species, platypuses have been considered extinct on mainland South Australia since the mid-1970s.
They are found on Kangaroo Island, with some sightings in the Riverland during the 1990s and more recently in 2018.
There are records of them living along the River Torrens in the early 1800s.
Green Adelaide Board Presiding Member Professor Chris Daniels said the scoping study would help identify areas along the waterway for potential reintroduction and population.
It would also involve a reintroduction risk analysis.
"We know that issues of opera house (fishing) traps, pumps and animals like foxes are obstacles to a successful reintroduction," he said.
"The platypus is an umbrella species and if we can successfully reintroduce this iconic Australian animal to Torrens it means a healthy waterway with benefits for other species like long-neck turtles and native water rats."
Adelaide Lord Mayor Sandy Verschoor said council was focussed on creating "a clean, green and healthy city" with a number of similar programs and initiatives designed to improve biodiversity.